In the combustion of a fuel, such as coal, oil, peat, waste etc, in a combustion plant, such as a power plant, a hot process gas is generated, often referred to as a flue gas, containing, among other components, carbon dioxide (CO2). The negative environmental effects of releasing carbon dioxide to the atmosphere have been widely recognized, and have resulted in the development of processes adapted for removing carbon dioxide from the hot process gas generated in the combustion of the above mentioned fuels.
WO 2006/022885 relates to a process for removing CO2 from a flue gas. In the process of WO 2006/022885, flue gas is initially treated by means of conventional air pollution control processes, such as by means of particulate collectors, devices for NOx and SO2 control, acid mist capturing devices etc. Flue gas leaving the conventional air pollution control treatment typically holds a temperature of about 40-80° C. The next step of the process involves cooling of the flue gas to a temperature of, preferably, 0-25° C. In this step, which is often referred to as direct contact cooling, cooling is accomplished by means of cold water. Following cooling, the flue gas is forwarded to a CO2 absorber, in which the actual CO2 removal takes place by bringing flue gas into contact with a low temperature ammoniated slurry or solution having a low carbon dioxide content. This allows absorption of CO2 from the flue gas into the ammoniated slurry or solution. The flue gas leaving the CO2 absorber contains very small amounts of pollutants and carbon dioxide. The CO2 rich ammoniated slurry or solution is regenerated in a regenerator, in which the carbon dioxide is stripped, at a temperature of about 50-200° C. and under high pressure, to form a concentrated CO2-rich stream at the regenerator overhead.